1. Field of the Invention
This invention relates to a fuel oil (diesel), gas or petrol operated internal combustion engine with at least two combustion chambers separated by valves from its cylinder housing a piston, and having a suction valve and an exhaust valve both opening to the cylinder, and a crankshaft. The invention also relates to a method to control the combustion process of a fuel oil (diesel), gas or petrol operated internal combustion engine provided with at least two combustion chambers separated by valves from its cylinder housing a piston, and having a suction valve and an exhaust valve both opening to the cylinder, and having a crankshaft, wherein said combustion process achieved in said combustion chambers separated by valves from its cylinder is built up by sub-processes including HCCI (Homogeneous Charge Compression Ignition) and CAI (Controlled Autoignition).
2. Brief Discussion of the Related Art
Before treating the problem to be solved by the invention, the meaning of HCCI (Homogeneous Charge Compression Ignition) process is to be defined. This is doubly necessary so as a great confusion can be observed in the technical field of ignition processes. In this patent application all ignition processes established by compression ignition of a (comparatively) homogeneous fuel charge, independently of the fuel type, will be mentioned as HCCI ignition process.
Operating cycle of combustion engines involves losses due to different reasons resulted in utilizing less portion of introduced heat energy as mechanical power.
Several attempts have been made for decades to eliminate losses incurring due to constructional solutions of combustion engines. Decreasing losses namely would lead to fuel reduction, improved workload as well as to a more balanced running of the engine, moreover, extremely high power engines having low relative weight and operating at high rotational speed could be built, the specific power factors would be improved and less exhaust gases and harmful materials would be emitted.
Substantial losses of reciprocating piston engines (Otto-engines, Diesel-engines and gas-engines) are as follows: high frictional loss, finite combustion rate (heat transfer does not occur at constant volume), losses occurring through the cylinder wall and imperfect expansion of combustion gases (it does not last up to the ambient pressure and temperature). Losses of a petrol engine are summarised according to F.A.F. Schmidt in Table 1.
TABLE 1Degree in percentDenotationReason of loss(%) of heat valueIFriction ~4IIWork of charge's change, wall ~5loss, finite combustion rate,etc . . .IIIImperfect expansion of~13combustion gases (not up tothe environmental pressure)IVImperfect expansion of~22combustion gases (not up tothe environmental temperature)VIrreversibility of combustion~25process (expansion could notlast till 0 K)Total~69
Losses denoted by I. and II. constitute power losses and losses denoted by III., IV., and V. are substantial losses. These losses are showed in a p-V diagram (see FIG. 9a.) and in a T-S diagram (see FIG. 9b.).
In the case of cylinder-piston-crankshaft engines the mechanical power yielded by the working process, and so the efficiency at a given compression rate, is the highest, if the combustion process takes place by the inner dead point at constant volume, after compression.
But, since the combustion rate is finite, the process of combustion lasts during the expansion stroke, extending also into the exhaust stroke (e.g.: in the case of diesel-engines).
This fact partly causes the power losses denoted by II. in Table 1.
Losses caused of finite combustion rate can be reduced by achieving a combustion process at constant volume.
This can be established by separating stroke volume from the combustion volume (combustion chamber) through valves.
Such a solution can be know from patent GB 505,713 disclosing an internal combustion engine of compression ignition type with a separate combustion chamber to receive the fuel, and one or more valves between the cylinder space and the combustion chamber. The valves are so moved as quickly to reduce the transfer cross-sectional area between the combustion chamber and the working space of the cylinder to its minimum value, which may be zero, shortly before the end of the compression stroke. After the working piston has passed its inner dead centre the transfer cross-sectional area gradually increases to its maximum in such a manner, that the pressure in the cylinder does not at any instant exceed a predetermined-pressure. The maximum value of the transfer crossectional area being retained till shortly before the end of the next compression stroke.
Patent document U.S. Pat. No. 5,115,775 discloses a two-cycle compression ignition engine including a first combustion chamber and a second combustion chamber located in said cylinder head, which combustion chambers being independently isolated from one another and from the clearance volume and each chamber defining a passageway in communication with said cylinder clearance volume, and an independently operated throttle valve for each combustion chamber and arranged for opening and closing said passageway associated with its respective chamber. The engine is provided by means for isolating the combustion process for one full 360 degree rotation of said crankshaft. The combustion chambers alternatively provide for expansion of combustion products in the respective chambers into the cylinder volume near top dead center upon each revolution of the crankshaft.
Solutions above—although contain the idea of compression volume(s) separated by valves from stroke volume and they could eliminate losses caused by finite combustion rate—are not suitable for achieving. Some problems are as follows:                combustion chambers are formed unfavourably in point of view of combustion process (particularly in U.S. Pat. No. 5,115,775), since the surface of combustion chamber depicted in the drawing is very large in relation to the volume thereof, resulted in a huge wall heat loss; the shape of the chamber does not enable to form a whirl in order to mix the injected fuel and the air;        in both solutions—but particularly in GB 505,713, where the applicant wants to adjust the pressure in the cylinder by means of choking (that is an irreversible pressure drop, that is a part of the pressure already built and achieved so hardly, will be lost)—huge choking losses are occurred,        in both solutions—but particularly in U.S. Pat. No. 5,115,775—an extinctive effect acting to the combustion process is occurred because of the surface/volume rate of combustion chamber, the combustion will be incomplete particularly next to the wall surface, resulted in very large unburnt hydrocarbon and interstage combustion product content of the exhaust gases.        
In addition, the solutions above:                do not provide a motor suitable for achieving HCCI ignition process,        do not solve the problems associated with existing petrol engines (low compression rate, power regulation by choking, inadequate efficiency at partial load, etc.)        neither above solutions offer any solutions to the problem of expansion of the gases up to a pressure still above the ambient pressure during the power stroke,        both have the risk of an imperfect or irregular combustion.        